Substituição total e parcial da ração comercial por farelo de soja fermentado durante a fase de berçário intensivo do camarão Litopenaeus vannamei

Abstract

The shrimp farming industry has been experiencing a movement towards intensification, which allows an increase in productivity with a better use and of natural resources. The growth of this sector is associated with the availability of quality post-larvae and juveniles. The use of intensive nursery is an important strategy for biphasic systems, providing better results during the grow-out phase, increasing survival and growth of farmed animals. Despite this, its use requires qualified labor and feeds with high levels of crude protein, which represent greater cost and a potential risk to the water quality, thus, to the health of the animals. Thus, it is necessary to develop strategies that allow the improvement of this culture system. This study aimed to evaluate the effect of replacing commercial feed with fermented soybean meal, using a commercial probiotic, composed of a mix of organisms, during the intensive nursery phase of L. vannamei carried out under commercial conditions. Thus, five replacement percentages were evaluated, as 0%, 25%, 50%, 75% and 100%. Zootechnical parameters, water quality, zooplankton density and standard plate count for bacteria of the genus Vibrio spp. in the nursery water were evaluated. It was possible to replace the commercial diet with 100% fermented soybean meal without affecting the final survival, specific growth rate (%) and feed conversion. It was possible to replace the feed up to 50%, without negative effect on average final weight (g) and daily weight gain (g/day). The final average productivity (kg/m³) and yeld (kg/m³) were affected only when the replacement level exceeded 75%. It was possible to replace up to 100% without prejudice to water quality parameters such as pH, dissolved oxygen (mg/L), total ammonia (mg/L), nitrite (mg/L) and alkalinity (mg/L of CaCO3). The total zooplankton density was higher in the SJ25% treatment, when compared to the others, which did not differ (p>0.05). The standard plate count of Vibrio spp. was not influenced by the different replacement levels, the exception being the SJ50% treatment, which reached the highest value (p<0,05). The results indicate that the use of fermented soybean meal can be used as food for L. Vannamei‘s post-larvae in intensive nursery. A maximum replacement rate of 50% is suggested, in order to maintain the pattern of development observed with the use of a protocol with commercial rations.